Almost none of these guys have wives or girlfriends or children.
Charles Whitman, the UTexas Tower shooter, was married, but murdered his wife.
There was a mass shooting in Atlanta by a bankrupt Day Trader years back, but he was actually the prime suspect in the murder of his first wife, and his (or her) mother, too, as I recall.
Terry Nichols, who assisted Tim McVeigh at the OKC truck bombing, was married twice and had 3 children.
In Nichols case, though, I think he was essentially a weak personality who allowed McVeigh to manipulate and intimidate him.
During the autopsy Whitman was found to have a brain tumor that caused the bizarre and murderous behavior. Although he was a mass murderer, he does not fit the classic pattern of a mass murderer.